Ps just in order to understand better what an armlock works and an iriminage doesn't (btw exactly the same type of suggetions also another member stated here: http://www.aikiweb.com/forums/showpo...2&postcount=42 - he suggested armlock and indicated iriminage as the least usable, and I personally find that very well said and evidently derived from experience against attackers who really try to get at you )

In both cases you go lateral. The differences are:

IRIMINAGE:
1) one of your arms is on his neck, totally unusable
2) your other arm is outstretched, dangling at the height of your foes' hips: that's where your arm was supposed to "hold" his wrist - but alas! no wrist there: he rechambered in a fraction of a second, and with a vehement force. And if you don't know this, you may even risk of staying there like a puppy who doesn't know what to do next because you feel puzzled: why this thing that worked marvels on the dojo does utterly nothing now?
3) you're fully exposed, as soon as he turns on his hips, he hits you in a grandiose manner...

ARMLOCK:
1) both your arms are in front of you, readly available to parry whatever
2) even if he rechambered, you can still shove one of your arms (the one that would have been on his neck) into his bent elbow - even better you may throw a punch at him (say an "atemi"...) as you fight your way to penetrate his bent elbow - and this round it will be him to be "puzzled".
3) your other arm can grab his wrist because it is not at his hips height but at his face height. In any case you're not fully exposed, both your arms can still protect you were he fast enough to turn on his hips and throw punches at you.

In both cases it is a dangerous situation (and therefore, one more reason to use stuff that is not too sophisticated in order to minimize chances at least as far as possibile), and it is indeed regrettable that in dojos we are never taught to deal with realistic dynamics, to the extent we may be utterly uncognizant of them.
This may spell disaster if one ever has the misfortune to face a real attacker who is not totally incompetent or drunk.